Whether you need brakes or not depends on how big of tank you put behind the tractor, if you go for the biggest tank the tractor can pull up the hill you better get brakes for going down the hill.


We need more info to know how big of tank you can pull. There is a huge disparity in what a "120 hp" tractor can handle.

For starters are we talking 120 pto hp or engine?

2wd or mfwd?  
Duals/singles? 
How much does this tractor weigh?
Whats it got for a transmission? 
Are you gonna pull knives or spray on top?


If its mfwd and duals, weighs good (14,000 lbs with the duals on would be a pretty good #), has a powershift or at least a partial power shift with syncronized gears you could maybe go up to 4800 gal but you'll definitely want brakes on the tank and it'd be best if they were hooked to the tractor brake pedal.